Robtex

Up: 2600:1800::/48
Can't show all results, try to descend to a more specific CIDR
Down left: 2600:1800::/50
Down right: 2600:1800:0:4000::/50
(Some of the IP numbers are capped at 3 entries)

IP	Type	Hostname
2600:1800::1	PTR	ns0.dnsmadeeasy.com
2600:1800::1	A	ns0.malytic.com
2600:1800::1	A	ns1.rikardos.co.uk
2600:1800::1:3	PTR	aurora.rhodium.host
2600:1800::1:5	PTR	ns1.apexis.ch
2600:1800::1:6	PTR	ns0.department7.co.uk